Document Detail


Resistance exercise load does not determine training-mediated hypertrophic gains in young men.
MedLine Citation:
PMID:  22518835     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We have reported that the acute postexercise increases in muscle protein synthesis rates, with differing nutritional support, are predictive of longer-term training-induced muscle hypertrophy. Here, we aimed to test whether the same was true with acute exercise-mediated changes in muscle protein synthesis. Eighteen men (21 ± 1 yr, 22.6 ± 2.1 kg/m(2); means ± SE) had their legs randomly assigned to two of three training conditions that differed in contraction intensity [% of maximal strength (1 repetition maximum)] or contraction volume (1 or 3 sets of repetitions): 30%-3, 80%-1, and 80%-3. Subjects trained each leg with their assigned regime for a period of 10 wk, 3 times/wk. We made pre- and posttraining measures of strength, muscle volume by magnetic resonance (MR) scans, as well as pre- and posttraining biopsies of the vastus lateralis, and a single postexercise (1 h) biopsy following the first bout of exercise, to measure signaling proteins. Training-induced increases in MR-measured muscle volume were significant (P < 0.01), with no difference between groups: 30%-3 = 6.8 ± 1.8%, 80%-1 = 3.2 ± 0.8%, and 80%-3= 7.2 ± 1.9%, P = 0.18. Isotonic maximal strength gains were not different between 80%-1 and 80%-3, but were greater than 30%-3 (P = 0.04), whereas training-induced isometric strength gains were significant but not different between conditions (P = 0.92). Biopsies taken 1 h following the initial resistance exercise bout showed increased phosphorylation (P < 0.05) of p70S6K only in the 80%-1 and 80%-3 conditions. There was no correlation between phosphorylation of any signaling protein and hypertrophy. In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure resulted in similar hypertrophy as a heavy load lifted to failure.
Authors:
Cameron J Mitchell; Tyler A Churchward-Venne; Daniel W D West; Nicholas A Burd; Leigh Breen; Steven K Baker; Stuart M Phillips
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2012-04-19
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-07-03     Completed Date:  2012-12-07     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  71-7     Citation Subset:  IM    
Affiliation:
Exercise Metabolism Research Group, Department of Kinesiology, McMaster Univ., 1280 Main St., West, Hamilton, Ontario, L8S4L8, Canada.
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MeSH Terms
Descriptor/Qualifier:
Biopsy
Humans
Hypertrophy
Male
Muscle Contraction / physiology
Muscle Proteins / metabolism
Muscle Strength / physiology*
Muscle, Skeletal / anatomy & histology,  cytology,  physiology*
Phosphorylation
Resistance Training / methods*
Ribosomal Protein S6 Kinases, 70-kDa / metabolism
Signal Transduction / physiology
Weight Lifting / physiology
Young Adult
Grant Support
ID/Acronym/Agency:
//Canadian Institutes of Health Research
Chemical
Reg. No./Substance:
0/Muscle Proteins; EC 2.7.11.1/Ribosomal Protein S6 Kinases, 70-kDa
Comments/Corrections

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